Fill prepared and cooled tart shell with half of Chocolate Cream Filling, and smooth with an offset spatula. Slice bananas 1/4 inch thick, and arrange slices in tight concentric circles over filling. Spread remaining filling evenly over banana slices.
Whisk cream and powdered sugar with an electric mixer fitted with whisk attachment until medium-stiff peaks form. Dollop whipped cream evenly over filling. Chill up to 4 hours before serving. Garnish, if desired.